Electrospinning is a technique known in the art for producing articles composed of polymer fibers. See U.S. Pat. No. 4,323,525. More recently, U.S. Pat. No. 7,276,271 disclosed a fibrous polymer tubular structure. Substrates with nanoscale aligned geometries are disclosed in U.S. Pat. No. 6,676,675. The use of electrospun fibrous polymer grafts in medical applications is disclosed in U.S. Pat. No. 7,172,765.
Other efforts have focused on tubular grafts made of biologically derived materials. See, for example, U.S. Pat. No. 7,214,242. Modified electrospinning methods for forming directed fibers are also disclosed in U.S. Pat. No. 7,135,134. PCT Publication Nos. WO 2007/146261 and WO 2007/090102 disclose various aspects of polymer fibrous scaffold sheets and tubes.
However, there is a need in the art for fibrous polymer scaffolds having multiple layers that provide flexibility and tensile strength in multiple directions. There is also a need to provide multiple layer fibrous scaffolds in which the layers will not de-laminate during use. There is a further need in the art for compositions that can promote the growth or regrowth of tissue or replace damaged tissue in a subject. Such scaffolds provide stability in a wide range of applications, particularly biomedical applications. Further, there is a need for apparatuses designed to manufacture such scaffolds. The present disclosure addresses these and other needs.